[In vitro activity of fusidic acid in combination with various antibiotics against Staphylococcus epidermidis]

Abstract

In vitro antibacterial activity of fusidic acid (FUC) in combination with cefotaxime (CTX), imipenem (IMP), gentamicin (GEN), amikacin (AKN), rifampin (RIF), fosfomycin (FOS), vancomycin, pefloxacin (PEF) was studied against 19 presumably pathogen meti-R Staphylococcus epidermidis strains. The study was carried out by means of a microtiter checkerboard method (FICs index, 19 strains) and killing-curves (3 strains). FUC x GEN, FUC x AKN and FUC x IMP combinations were found synergistic with achievable therapeutic concentrations for IMP (MIC in the combination less than 1 microgram/ml) but with higher concentrations for AKN and GEN (greater than or equal to 8 micrograms/ml). FUC x PEF combinations were regularly antagonistic. FUC x RIF, and FUC x FOS combinations showed a modal FIC greater than or equal to 4 but were found respectively additive and synergistic with killing-curve method. Remaining FUC combinations results were variable. FUC resistant mutant frequency, studied for 3 S. epidermidis strains, was similar as S. aureus one's (0.5.10(-7) a 2.5.10(-8)).